1. Field of the Disclosure
The present disclosure relates to a method of producing a tooling to be used for manufacturing a rigid panel formed of polymer matrix composite material, a method of manufacturing a rigid panel, an a rigid panel.
2. Description of the Related Art
A typical gas turbine engine has a substantial number of electrical components which serve, for example, to sense operating parameters of the engine and/or to control actuators which operate devices in the engine. Such devices may, for example, control fuel flow, variable vanes and air bleed valves. The actuators may themselves be electrically powered, although some may be pneumatically or hydraulically powered, but controlled by electrical signals.
Electrical power, and signals to and from the individual electrical components, is commonly transmitted along conductors. Conventionally, such conductors may be in the form of wires and/or cables which are assembled together in a harness. In such a conventional harness, each wire may be surrounded by an insulating sleeve, which may be braided or have a braided cover.
The harnesses are assembled from individual wires and cables which are held together over at least part of their lengths by suitable sleeving and/or braiding. Individual wires and cables emerge from the sleeving or braiding to terminate at plug or socket connector components for cooperation with complementary socket or plug connector components on, or connected to, the respective electrical components.
Each conventional harness comprises a multitude of insulated wires and cables. This makes the conventional harness itself bulky, heavy and difficult to manipulate. The conventional harnesses occupy significant space within a gas turbine engine (for example within the nacelle of a gas turbine engine), and thus may compromise the design of the aircraft, for example the size and/or weight and/or shape of the nacelle.
Conventional harnesses comprise a large number of components, including various individual wires and/or bundles of wires, supporting components (such as brackets or cables) and electrical and/or mechanical connectors. This can make the assembly process complicated (and thus susceptible to errors) and/or time consuming. Disassembly of the conventional harnesses (for example removal of the conventional harnesses from a gas turbine engine during maintenance) may also be complicated and/or time consuming. Thus, in many maintenance (or repair or overhaul) procedures on a gas turbine engine, removal and subsequent refitting of the conventional electrical harness may account for a very significant portion of the operation time and/or account for a significant proportion of the potential assembly errors.
The electrical conductors in the conventional harnesses may be susceptible to mechanical damage. For example, mechanical damage may occur during installation (for example through accidental piercing of the protective sleeves/braiding) and/or during service (for example due to vibration). In order to reduce the likelihood of damage to the conductors in a conventional harness, the protective sleeves/braiding may need to be further reinforced, adding still further weight and reducing the ease with which they can be manipulated. Similarly, the exposed electrical connectors used to connect one conductor to another conductor or conductors to electrical units may be susceptible to damage and/or may add significant weight to the engine.
Similar problems can be associated with fluid passages carrying e.g. hydraulic or pneumatic fluid.
Accordingly, it has been proposed to replace conventional harnesses with rigid panels, typically formed of composite material, in which electrical conductors and/or fluid passages are embedded in the panel. See, for example, US 2013/160458 (hereby incorporated by reference) for a description of such a panel or “raft”.
Transferring electrical signals using an embedded electrical system of a rigid panel can provide a number of advantages over transferring electrical signals using a conventional harness. For example, during assembly and in use, such panels may provide greater protection to their electrical conductors than conventional harnesses. Further, the use of such panels may significantly reduce the build and maintenance times of an engine, and/or reduce the possibility of errors occurring during such procedures. The panels can also provide weight and size advantages over conventional harnesses. Similar advantages accrue when fluids are transferred using the embedded fluid system of the rigid panel.
Such panels can conveniently be formed by moulding a polymer matrix composite material against a mould which is a “negative” of the final panel. The mould can be formed directly, e.g. from tooling board or aluminium alloy, or it can itself be formed by moulding a (typically composite) material against a pattern which is a “positive” of the final panel.
The panels can be of large size (e.g. several metres in length) and typically have a curved shape which allows them to be wrapped around at least a part of a circumference of the engine (e.g. around a fan case). In addition, it is common to add additional detailed patterns/moulds to the larger pattern/mould in order to form smaller details of the panel.
A problem arises, however, in that production of the tooling cannot be started until a final design for the panel is complete. This can delay the production of the tooling with a corresponding impact on the length of the entire the design-to-manufacture program for the finished panel. Subsequently, if modifications to the panel are required, then these can be costly and time-consuming to implement in the tooling.